These 6spds don't seem to work as well with a gas engine from my limited experience with the Yukon(vs my 6spd/Duramax). It never seemed to be in the right gear wherever I was driving, as if you needed to kick it down to a lower gear to wake the engine up. I guess they're trying to squeeze all the mileage they can out of it, and the tranny is set-up as such. All in all, I don't think it was anymore economical than my diesel and imo, not worth 61K(maybe 40-45K).

I know exactly what you are talking about. My 08 Sierra Denali has the 6.2 and six speed. I had mine for about two months before I had it tuned. Woke it up big time, my mileage went up 15% and the thing shifts wonderfully now. The down side to this is GM knows if the thing has a tune and the warranty is effectively voided. You can program a spare ECM, swap it out as needed, but the tranny has its own control module inside the tranny, so you can't swap it out very easily. It can only be tuned via on board lap top and interface cables. There is a guy who sells a kit now, where I bought mine from. He sends you a control unit that you just plug into the interface adapter, then you down load the tune for the engine and tranny. You drive the rig, copy the monitoring file to a disk and email it back to him. He looks the data over, tweaks the tune as needed, then sends the file back to you. They you just down load the updated file. He also includes five other tuning profiles based on the data you send him and all you do is select the tune you want to run (towing, racing, economy, etc). My truck does not drive anything like it did stock. Pretty slick. I don't like to advertise, so if anyone is interested, PM me and I'll give you his name and web sight.

Finding Z rated tires for this thing is a point of contention. I’ve been looking, as I know I’ll need some before long. I want to go with a run flat, as the car does not have a spare. The Z06 forum guys tend to like PS2’s and Bridgestone’s, but most of the guys BS’ing on the forums live somewhere warm. I’ll check out the tires you mention. I need 275/30/19 and 335/30/19’s. 345 will fit as well. 325 are also an option, but probably not quite wide enough for acceleration traction. I was spinning shifting into second at 5000 rpms / 50 mph and redline is 7000. I spun a bit shifting into third too, but won’t mention the speed. It definitely got my attention to say the least. Hopefully, they will not spin as easily with warmer temps.

Are you dead set on runflats? They're heavier, more expensive, and ride harsher than normal tires, which I'm sure you know. A lot of people I know with vehicles that come with runflats switch them out once they're done, and then keep a fix-a-flat kit of some sort in the trunk (some get the fancy air pump/sealent combo, some just the fix-a-flat can). I know once I need new tires I'm gonna ditch the runflats.

Another thing to consider, especially since you're living in Alaska, is a runflat is good for 50 miles once it loses pressure. When you're out on a trip or cruise, will 50 miles get you anywhere useful?

Anyhoo, it only snows about twice a year in Tacoma, and I don't really plan on driving my roadster those days, but it is my daily driver. I need new front tires (they are a different size than the back). After independently identifying the Continental DWS and then seeing JohnK's recommendation, it occurred to me that maybe I really don't need "all season" tires, and that perhaps the DW would offer better performance and wear. I'm unsure about how to weight road temperature when looking at this question.

I really don't want to spend more than about $400 all-in for a pair of tires, so any of you elitists can just take your suggestions for Bridgestone Potenzas elsewhere.

Do you do much cold weather driving? It's not just snow that summer performance tires are bad in, it's cold weather. Anything below maybe 45 degrees F and they turn hard and lose a lot of grip.

Wear differs between various models and brands, but generally speaking, summer performance will wear quicker than all seasons, but offer more grip, it's a trade-off. So your switch to the Contis should gain you performance (a fair amount) but will wear quicker.

Also, if you're just getting new fronts, I wouldn't recomend mis-matching with the rears. The different grip offered by a different kind of tire could cause unwanted handling changes and even make the car unstable during handling (depending on if it indroduces over or understeer). If you're only replacing 2, you should match to what you have. Or get 4 new tires. That would be the rational advice anyway, you are free to do whatever you want